1. Field of the Invention
The present invention relates to two dimensional semiconductor image sensors, and in particular to such an image sensor with controlled or regulated integration time.
2. Description of the Prior Art
A two dimensional semiconductor image sensor with a number of sensor elements disposed in rows and columns on a semiconductor substrate is described, for example, in the article "Low-Noise MOS Area Sensor With Antiblooming Photodiodes," Ohba et al, IEEE Journal of Solid-State Circuits, Vol. SC-15, No. 4, August, 1980 at pages 747 through 752. In the image sensor described therein, all lines are controllable by means of allocated parallel outputs of a vertical shift register for selecting the individual sensor elements. The outputs of the sensor elements are connected in the selected state to the column lines and a sensor output is provided for a sequential readout of the signals of the sensor elements transmitted in parallel on the column lines which correspond to the amount of optically-generated charge carriers resulting from light incident on the sensors.
A disadvantage of such conventional image sensors is that the integration time, which is the time during which the sensors are connected to an operating voltage so that charge carriers can be generated within the sensors, is fixed and cannot be changed in order to adapt to different uses of the image sensor and different types of incident light to which the sensors may be exposed.